1. Field of the Invention
The present invention relates to a plasma display panel, and more specifically, to a plasma display panel having a plurality of closed rib units, each of which including at least two sub-pixel units.
2. Description of the Prior Art
A plasma display panel (PDP) is one kind of flat display panels using gas discharges to create brilliant irradiation. Since the PDP has the advantage of a thin and large-scaled design, and low radiation, it is a mainstream large-scaled display panel.
For example, a plasma display panel is disclosed in U.S. Pat. No. 6,373,195B1 and its detailed structure is described as follows. Please refer to FIG. 1 and FIG. 2. FIG. 1 is an exploded diagram of a plasma display panel disclosed in U.S. Pat. No. 6,373,195B1. FIG. 2 is a top view of the plasma display panel shown in FIG. 1. As shown in FIG. 1 and FIG. 2, a PDP 10 comprises a front substrate 12, a rear substrate 14 arranged in parallel with and opposite to the front substrate 12, and a discharge gas filled between the front substrate 12 and the rear substrate 14. Additionally, a plurality of X electrodes 16 and a plurality of Y electrodes 18 are formed on the front substrate 12, and a plurality of parallel address electrodes 20 are formed on the rear substrate 14. The X electrodes 16 are arranged in parallel with and interlaced with the Y electrodes 18, and the address electrodes 20 are perpendicular to the X electrodes 16 and the Y electrodes 18. Each of the X electrodes 16 includes a bus electrode 16a, a plurality of sustain electrodes 16b connected to one side of the bus electrode 16a, and a plurality of sustain electrodes 16c connected to the other side of the bus electrode 16a. Likewise, each of the Y electrodes 18 includes a bus electrode 18a, a plurality of sustain electrodes 18b connected to one side of the bus electrode 18a, and a plurality of sustain electrodes 18c connected to the other side of the bus electrode 18a. The sustain electrodes 16b of each X electrode 16 are opposite to the next sustain electrodes 18c, while the sustain electrodes 16c of each X electrode 16 are opposite to the next sustain electrodes 18b. 
As shown in FIG. 1, the PDP 10 further comprises a plurality of parallel ribs 22, and a plurality of ribs 24 connected between two adjacent ribs 22, so that a plurality of sub-pixel units 26, 28 and 30 is defined between the ribs 22 and the ribs 24. Additionally, each of the sub-pixel units 26 is a red sub-pixel unit R that is coated with red phosphors, each of the sub-pixel units 28 is a green sub-pixel unit G that is coated with green phosphors, and each of the sub-pixel units 30 is a blue sub-pixel unit B that is coated with blue phosphors. Furthermore, three sub-pixel units, which are arranged in a delta and include a red sub-pixel unit R, a blue sub-pixel unit B, and a green sub-pixel unit G, constitute a pixel unit.
After the discharge gas in the sub-pixel units 26, 28 and 30 is applied with a discharge voltage, the discharge gas is excited and ionized to produce ultraviolet light. Thereafter, the ultraviolet light irradiates the red, green, and blue phosphors so that the sub-pixel units 26, 28, and 30 can emit red, green, and blue visible light. Additionally, the discharge voltage used to excite and ionize the discharge gas is varied with the space available to the discharge gas, and usually, the discharge voltage becomes smaller if the space available to the discharge gas gets larger. Therefore, an increase in the discharge voltage will reduce power consumption of a PDP. However, since each sub-pixel unit of the PDP 10 is defined between the front substrate 12, the rear substrate 14, two adjacent ribs 22, and two adjacent ribs 24, the space available to the discharge gas in each sub-pixel unit is limited to the space where each sub-pixel unit occupies. As a result, the discharge voltage of the discharge gas in each sub-pixel unit 26, 28, or 30 is much higher, so that an operating voltage of the PDP 10 is high and the power consumption of the PDP 10 is therefore considerable.